Marine diatom and silicoflagellate biostratigraphy of the type Delmontian Stage and the type Bolivina obliqua Zone, California

Investigation of the marine diatom and silicoflagellate biostratigraphy of the type Delmontian Stage and and type Bolivina obliqua Zone in California shows that the type Delmontian Stage is equivalent to part of the supposedly older Mohnian Stage and is early late Miocene. The type Bolivina obliqua Zone, which conformably overlies the type Mohnian Stage, appears to be early Pliocene.